As set forth in copending application Ser. No. 561,323, now U.S. Pat. No. 4,552,319 child restraint systems for automobiles are frequently designed to employ conventional seat belt and shoulder harness for strapping the child onto a child's seat placed on a conventional passenger seat, or in the case of children who do not require an auxiliary child's seat, the harness may be applied to the child as in the case of an adult. In either case, where the child's feet do not touch the floor of the vehicle, the belt and shoulder harness restraining system may be required to hold the auxiliary seat, or child without such seat, against moderate deceleration or turning of the vehicle to prevent, forward pitching or lateral auxiliary seat tipping.
Where inertia responsive retractors are employed to accommodate free forward leaning of the passenger in the absence of sudden deceleration, such systems may be ineffective to adequately restrain children, either in auxiliary seats or otherwise, where foot bracing by the child is unavailable. In order to meet this problem, various means have been employed to lock the retractor when the restraint system is applied to a child as by a manual lever, push button or other device located on the retractor housing adjacent the reel latch. Such solution has not been entirely satisfactory, particularly where the retractor housing is at an inconvenient location.
Accordingly, vehicle manufacturers have recognized the need for some means to convert a vehicle sensitive inertia (VSI) retractor to an automatic locking retractor (ALR) mode which would be convenient for the adult applying the restraint system to a child; for example, in response to fully extracting the webbing whereupon retraction by the wind up spring would ratchet the latch to an automatic locking condition when all webbing play has been taken up with the child, including an auxiliary seat, in requiring restraint position.
Applicants of said copending application have developed three alternative viable mechanical solutions to the problems posed by vehicle manufacturers, one of which is web sensitive and the other two gear drive. In each of the embodiments a conventional inertia latch mechanism is adapted to permit free reeling of the web in and out against the retraction spring with a latch bar adapted to engage ratchet teeth locking the reel against webbing extension in response to predetermined deceleration of the vehicle through an inertia latching mechanism thereby functioning in a vehicle sensitive inertia mode, (VSI).
In each of the embodiments a mechanism is provided to supplement the inertia element to bias the latch bar toward an engaging position independently of deceleration whereby the webbing is locked against extraction but can ratchet in a retraction direction under the tension of the retractor wind up spring thereby establishing an automatic locking retractor mode, (ALR), operative to restrain a child with or without an auxiliary seat chair independently of inertia forces.
In each embodiment full extension of the belt webbing is adapted to establish the ALR mode and to retain such mode upon partial retraction to a child restraining position, and until release of the child from the seat followed by full retraction of the webbing disables the automatic locking mechanism and restores the VSI mode.
In one of the embodiments the level of belt webbing wound on the reel is employed to trigger the ALR locking mechanism at both extremities with a web level sensitive finger establishing the ALR mode at the minimum radius of belt webbing corresponding to full extraction and to restore the VSI mode at maximum radius corresponding to full retraction.
In second and third preferred embodiments an extension of the reel spindle is provided with a miniature pinion gear adapted to actuate an internal ring gear through a fractional part of one revolution between full belt extraction and full retraction. In one gear embodiment an internal segmental cam on the ring gear is adapted to actuate a detent/lever mechanism for biasing the latch bar to an ALR mode or to free it for conventional VSI operation.
In the other gear embodiment, the pinion drives an annular ring having parallel external circumferential cam tracks of different radial level engaged by the finger of a lever for biasing the latch bar to an ALR mode at minimum radius and freeing it for VSI operation at minimum with a ramp transition provision between the tracks at the extremities of belt extraction and retraction.
Such prior constructions did not include a provision for overtravel in the VSI mode following its initial re-establishment upon partial retraction of webbing beyond operative belt connection extension, such as desirable to accommodate loss of stop button limiting webbing retraction upon engaging a cover slot. In addition there was no provision for delaying transition to ALR mode upon full webbing extraction, pending a slight retraction, as has proved disirable to assure proper operation under all tolerance variations of assembly.